Injection molding machine



July 19,1949. BAUMAN 2,476,272

INJECTION MOLDING MACHINE Filed June 4, 1945 2 Sheets-Sheet 1 @WL 95,aos

FIG. 1

M INVENTOR. I

@W/MIAK July 19, 1949. M. A. BAUMAN 2,476,272

INJECTIBN MOLDING MACHINE 7 Filed June 4, 1945 2 Sheets-Sheet 2 FIG 2 INV EN TOR.

%M/WW Patented July 19, 1949 INJECTIUN MOLDING MACHINE Morton A. Bauman,Cleveland, Ohio, assignor to The Lees-Bradner Company, Cleveland, Ohio,a corporation of Ohio.

Application June 4, 1945, Serial No. 597,559

2 Claims.

materials and is particularly adapted to the molding of materials whichbecome soft and moldable upon the application of heat such as thethermoplastic and thermo-setting materials now being extensively usedfor molding many parts and devices.

An object of the invention is to provide an improved molding apparatuswhich will be extremely safe in producing molded articles.

Another object is to provide an improved molding apparatus which will beextremely simple in its operation.

Another object is to provide an improved molding apparatus which will becomposed of few and rugged parts.

Another object is to provide an improved molding apparatus which may bereadily and economically manufactured.

Another object is to provide an improved molding apparatus which willeffectively protect the operator.

Another object is to provide an improved molding apparatus which mayeasily be operated.

Another object is to provide an improved molding apparatus which will becompact and occupy little floor space.

Another object is to provide an improved molding apparatus in which suchparts as need to be disassembled for cleaning and the like will bereadily accessible.

Another object is to provide an improved molding apparatus which will becapable of molding articles under extremely high pressures.

Another object is to provide an improved molding apparatus in whichsections of the mold will be eiiectively maintained in closed positionduring the entire molding operation.

Another object is to provide an improved molding apparatus which will beneat and attractive in appearance.

Other objects will hereinafter appear.

The invention will be better understood from the description of onepractical embodiment thereof, illustrated in the accompanying drawings,in which:

Figure 1 is a side elevation of a molding machine embodying the presentinvention;

Figure 2 is a central longitudinal sectional view of the machine ofFigure 1; and,

Figure 3 is a diagrammatic illustration of the control valves andcircuits of the machine of Figures 1 and 2.

The machine shown consists of a base, indicated generally at I, whichmay be a casting or 2 may consist of a welded frame with (or without) aprotecting cover and which supports the molding apparatus and enclosesthe drives and controls therefor.

Positioned on the top of the bases are two lengthwise extending tie orstrain bars 2 and 3, which also serve as supports and guides for variousparts of the molding mechanism and control apparatus. Upon these bars,adjacent their ends are mounted two fluid pressure cylinders 4 and 5,the tops of these cylinders also being connected by two more strain ortie bars 6 and 1 secured to the cylinders as by machine screws 8.

The first mentioned cylinder 4 operates the mechanism for injectingmaterial which is to be molded into the mold, while the second mentionedcylinder 5 is associated with the mechanism for closing and opening themold as desired, the injecting mechanism and mold being carried by thetie bars between the two cylinders, as will be hereinafter more fullydescribed.

Within cylinder 4 is a piston 9, having a piston rod I0 extendingthrough the apertured head H, secured to the inner end of the cylinder 4by machine screws IZ. A closed head I3 is secured to the opposite end ofthe cylinder 4 by machine screws M.

The piston rod Ill is secured to or formed integrai with an injectionplunger I5, by which material is delivered to the mold.

This material is supplied by gravity through a hopper l6, having a coverI7, and carried by a carriage l8 longitudinally movable upon bars 2 and3.

The carriage may be locked in position by means of a clamping block orbar 19 which may be drawn tightly against the underside of the bars 2and ,3 by a bolt 20, the thread of which is engaged by a thread formedin a worm wheel 2i. driven by-worm 22 on a shaft 23 to the outer end ofwhich is fixed a hand wheel 24.

The carriage has formed integrally therewith a cylinder 25 in which theplunger l5 reciprocates. and through an opening in the top of which thematerial to be molded may drop from the hopper The cylinder 25 hasflared discharge end 25 terminating in an outwardly extending flangewhich is attached by screws 21 to a heating cylinder 28, the forward endof which is provided with a nozzle-supporting piece 29 which carries anozzle 38 by which the material is delivered to the mold.

The heating cylinder and associated parts are supported on carriage [8by bracket-like supports 3!.

The interior of the cylinder 28 is enlarged considerably over the crosssectional area of the cylinder 25, and in this enlarged space ispositioned a somewhat fusiform or streamlined bailie or torpedo 32provided with a detachable head 33 and having in its interior anelectric heater 34.

Around the exterior of cylinder 28 is an electric heater 35 which isprovided with a covering of heat insulating material 36.

A similar electric heater 3! surrounds the nozzle supporting base 29 andis in turn surrounded with heat insulating material 38.

The carriage IS, on the end remote from the nozzle, is provided with abracket 39 carrying clamping jaws 40 which may be brought together toclamp upon plunger l5 by means of a threaded rod 4i having fixed to itsfront end a hand wheel 42.

Fixed to bars 2, 3, 6 and I, as by transverse bars it, is a verticalstationary centrally apertured platten 54, to which one mold section 45may be secured as by machine screws 46.

Co-operating with the stationary mold section is another and movablemold section 41, fixed by screws 48 to a movable platten 49 parallel tothe stationary platten and slidable along bars 2, 3, 6 and I.

The means for moving movable platten include a piston 55 reciprocable incylinder 5 and having a piston rod 5| extending through the innercentrally apertured head 52.

The piston rod has a head 53 clamped within a recess of the movableplatten 49 as by a perforated plate 54.

It will, of course, be understood that cylinder 5 has a closed outerhead 56 secured to it as by machine screws 51.

Apertured cylinder heads H and 52 each are provided with packing glandsand packing, indicated generally at 58.

A slidable protective cover or door 59 extends in front of the moldsection when the device is in operation, but can he slid to the left, infront of cylinder 5, when the operator changes or adjusts the moldparts.

The operation of the parts so far described is as follows:

Material, in granular form, is fed through the hopper l5 and dropsthrough the bottom part of this hopper into the injection cylinder 25.

It being desired to mold articles, the carriage i8 is locked in positionwith its nozzle 30 engaging mold section 45 by rotation of the handwheel 2 Door 59 is closed.

Pressure is first admitted to the outer end of cylinder 5, moving piston50 to the right and carrying the mold section 41 tightly against moldsection 45. After these sections are closed, pressure is maintained onthe outer end of piston 50 until the molded article has been finished,this pressure, of course, exerting greater force than that which will beexerted by the material within the mold tending to open the sections.

After the mold sections have been closed, pressure is admitted to theouter end of cylinder 4, moving piston 9 to the left, and thus carryingplunger l5 into the injection cylinder 25.

In passing the bottom of the hopper IS, the plunger carries before it acharge of granular plasticizable material, the stream of this mate rialdividing around the end 33 of the torpedo and passing between the heatedouter surface of the torpedo and the heated inner surface of cylinder28, where it is melted into a plastic condition.

After passing the end of the torpedo, the

'4 stream of now relatively fluid material converges to the injectionnozzle through which it enters the cavity of the mold.

The motion of piston 9 continues until the mold is completely filledwith material under adequate molding pressure.

At this time the motion of piston 9 is arrested and the pressureproduced by it on the material in the mold is retained for a sufficientperiod of time to permit the material to cool and harden or to set.

After this, pressure is released from the outer end of cylinder 4 andapplied to the inner end of this cylinder to move piston 9 to the right,releasing its pressure on the material in the injection cylinder andthereafter withdrawing the end of plunger 1 5 to allow more material todrop from hopper 15.

After the release of the pressure on plunger 15, pressure is releasedfrom the outer end of cylinder 5 and is applied to the inner end of thiscylinder, causing piston 50 to move to the left and pulling the moldsections 45 and 41 apart which permits the article which has been moldedto drop from between these sections and slide down and out through thechute 60 Where they may be received in any suitable container placed infront of the machine.

It will be understood that in molding thermosetting materials, the moldsections themselves may be equipped with heaters to furnish the heatnecessary for the reaction of the material within the molds.

Fluid pressure is again admitted to the outer end of cylinder 5 to closethe mold sections and then to the outer end of cylinder 4 to actuate theinjection plunger, thus repeating the molding cycle.

The operations of admitting fluid to the cylinders and the controltherefor is accomplished by parts of the apparatus within the base yetto be described.

If, for any reason, it is necessary to dismantle the nozzle or heatingcylinder parts, the operator need only turn the hand screw 24 to loosenworm wheel 2| upon the threads of the bolt 20. so that the carriage It!may be slid along bars 2 and 3. He then tightens hand wheel 42 to causeclamp sections 48 to grip the injection plunger l5 and admits fluidpressure to the inner end of cylinder 4, so that the outward motion ofpiston 9 retracts the entire carriage l8 and its associated parts,withdrawing the injection nozzle from the platen 38 and mold so that itis readily accessible.

After cleaning or repair, piston 9 can be caused to move inwardly toreturn the carriage [8 to its original position, where it is againclamped by actuation of hand wheel 24 and clamps 4B are released by theactuation of hand Wheel 42.

Electric power is supplied for operating the apparatus from any suitablesource, such as lines from an external power house, to a motor 6|positioned within the base I.

Mounted on the shaft 62 of this motor are three pumps 63, 64 and 65.Pumps 63 and 64 are designed to operate at the same pressure, and pump65 at a substantially higher pressure but to deliver much lower volumeof fluid than the first two mentioned pumps.

The pumps are supplied with fluid from tanks 66 and 61, also within thebase I, through conduits 58 and 69.

From the discharge side of pump 63 fluid passes through a conduit H! toa conduit 1 l.

A by-pass conduit 12 extends from conduit 10 to a hydraulic relief valveI3, from which the fluid may be returned by the conduit I4 to the tank66.

At the juncture of conduits I and I2 is positioned a check valve I5which prevents fluid being returned to the pump if the pressure inconduit I'I exceeds that of the fluid being discharged by pump 53.

The connections from pump 64 are similar to those of pump 63, consistingof an upwardly extending conduit 16 communicating through check valve 11with conduit II, there being a bypass branch 18 from conduit 16 to apressure relief valve I8 from which fluid may be returned by conduit 80to tank 61.

The ends of conduit II communicate with two control valves, these beingfour-way valves associated with the cylinders 4 and 5, the valve at theleft in the drawing and associated with cylinder ii being indicated bythe character BI and that associated with cylinder 4 by the character82.

Three outlets are shown from each valve.

From valve 82, a conduit 83 leads to the outer end of cylinder li, aconduit 84 leads to the inner end of this cylinder, while a fluid returnconduit 85 leads from the valve directly to the tank 66.

Similarly, from valve 8| a conduit 86 leads to the outer end of cylinder5, a conduit 81 leads to the inner end of cylinder 5, and the conduit 88communicates with the tank 61'.

The outlet from pump 65 consists of a conduit 853 connected to conduit86. A by-pass 90 extends from conduit 89 adjacent pump 65 to a pressurerelief valve BI, which, in turn, is connected by a conduit 92 to conduit80 through which liquid may be returned to tank 61.

Connected to conduit 85 is a pressure actuated switch 93 and a similarpressure actuated switch 54; is connected to conduit 83.

Two limit switches 95 and 95 are positioned adjacent the door 59 and areactuated by the door, so that they will be closed only when this door isin its protective position between the operator and the mold sections.Conveniently, one switch may be closed by the upper edge of the door andthe other by the lower edge.

These switches are safety devices and are connected in series in themain control circuit, so that the device cannot be actuated unless thedoor is closed or unless the switches are held manually. Two of them areprovided so that the operator cannot reach them both with one hand. Ifhe wants to operate them manually, he must remove both hands from themachine. Otherwise, he must close door 59, so he cannot close the moldparts upon himself.

Three other limit switches are positioned on the machine, two beingarranged for actuation by the motion of the mold closing piston rods orram 5| and one by the motion of the injecting piston rod or rain Ill.

The first is a limit switch 91 which is normally open and is closed onlyas the ram 5| advances the mold sections nearly to closed position. Inactual practice, this switch may be adjusted to close its circuit onlywhen the molds are not more than one sixteenth of an inch apart.

Another limit switch 98 is arranged to be actuated when the moldsections are fully separated.

The remaining limit switch 99 is actuated by the piston rod I!) orplunger I5 when this plunger is retracted to its fullest extent.

Two time delay relays I00 and IUI are positioned within the base of themachine, the former relay being arranged normally to close one circuitand open another, but to open its first mentioned circuit and break itssecond mentioned one when it is energized, and the latter relay beingarranged to close its circuit when energized.

The valve 8| contains two actuating coils or solenoids 8 I a and 8 lb.When coil 8 I a is energized the valve is moved into a position topermit fluid from pipe II to flow through pipe 86 to the outer end ofcylinder 5. When coil 8Ib is energized, the valve is moved to theposition in which liquid from pipe TI passes through pipe 81 to theinner end of cylinder 5.

Similarly, valve 82 has two coils or solenoids 82a and 82b; when theformer is energized, it permits liquid to flow from pipe II through pipe63 to the outer end of cylinder 4, while when coil 82b is energized,fluid is directed through pipe 84 to the inner end of cylinder 4.

When neither of the coils or solenoids of either valve is energized, thevalve assumes a neutral position in which the fluid from either end ofpipe 'II is returned through pipes 85 and 88 to the tanks 66 and ET.

The control circuits for actuating the device are illustrated in Figure3, which shows the main power lines bringing current to the apparatus atI '62 and I E13, these lines being connected to motor 6|, which isprovided with a control switch IM by which the motor may be started orstopped independently of the control of the other parts of theapparatus. The motor operates continuously while the machine is inoperation.

From conductor I83, a conductor I extends to switch 95, this beingconnected by conductor I06 to switch 96, from the latter of whichextends a conductor it? which branches to connect with the limitswitches 91 and 98, the opposite sides of these last mentioned limitswitches being connected together and to a conductor I88.

From conductor Iil'I, a branch Hi9 extends to a push button III] whichis normally open, but may be manually depressed to close its circuit,and around which is shunted a hold-in III. A conductor H2 extends fromthe push button to limit switch 88 and a conductor I I3 connects thiswith one end of coil 8 Id of valve BI.

A conductor I I4 extends from the other end of coil am to line I02.

Conductor IBIS is connected to one of the contacts of time-delay relayIIJI, and from the other contact of this relay a conductor H5 connectswith one end of coil Gib, the other end of this coil being connected toconductor I I4.

Conductor I08 is also connected to one end of the coil of time-delayrelay IIlI.

Wire I 26 extends from the other end of the coil IIlI to one of thenormally open contacts of timedelay relay I00.

A conductor II'I connects the other normally open contact of relay Iiiiiwith one end of coil 82b of valve 82, the other end of this coil beingconnected to conductor H4.

The end of conductor I08 is branched, the branches terminating at acontact of pressure controlled switch 93 and at a contact of pressurecontrolled switch as.

From the remaining contact of switch 33, a con-- ductor II'I extends toone of the normally closed contacts of ti1ne-delay relay Ill}, whilefrom the other normally closed contact a conductor H8 connects with oneend of coil 82a.

The other end of coil 82a is also connected to conductor H4.

The remaining contact of pressure control fications, and variationscoming within the scope of the appended claims.

I claim:

1. An injection molding machine comprising a frame, a mold carried bythe frame, an injection cylinder movably carried by the frame, aninjection piston, driving means for reciprocating the injection pistonwithin the injection cylinder, clamping means releasably clamping theinjection cylinder to the frame, and clamping means releasably clampingthe injection cylinder to the injection plunger.

2. An injection molding machine comprising a frame, a stationary holdercarried by the frame, a mold section secured to the holder, a secondmold section co-operating therewith, a movable support for said secondmold section carried by the frame, moving means connected to said secondsupport and arranged to move it toward and from the first mentionedsupport, an injection cylinder movably carried by the frame and havingan outlet movable into engagement with the '10 first mentioned moldsection, an injection plunger reciprocable in said injection cylinder,moving means connected to said plunger, a manually operable clampbetween the injection cylinder and the machine frame, and a secondmanually operable clamp between the injection cylinder and the plunger.

MORTON A. BAUMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,107,190 Shaw Feb. 1, 19382,187,212 MacMillin Jan. 16, 1940 2,246,414 McIntyre June 17, 19412,277,640 Harrington Mar. 24, 1942 2,304,461 Knowles Dec. 8, 19422,318,031 Tucker May 4, 1943 2,355,613 Wacker Aug. 15, 1944 2,372,833Jobst Apr. 3, 1945

